In order to support the driver of a motor vehicle in fulfilling his tasks in road traffic, methods for automatic traffic sign recognition and driver alerting with the aid of a suitable optical-based detection system have recently been developed and brought onto the market by diverse original parts manufacturers and by manufacturers of portable navigation units.
Portable navigation systems are typically based on signals from satellite-based systems (GPS, Galileo, GLONASS, etc.) in conjunction with map data in order to supply the driver with information regarding traffic signs (as recorded in the map data base). Other proposed systems make use of a camera-based optical recognition in order to improve the recognition and robustness. In contrast thereto, the vehicle manufacturers themselves chiefly make use of front view camera devices and signal combination with data that relate to the current driving state of the vehicle. Signal combination with navigation devices is also proposed as an option.
In many cases speed restrictions and signs for regulating overtaking maneuvers after the respective road has been left no longer pertain to a vehicle and hence are no longer valid. Alerting of the driver to such traffic information therefore becomes superfluous after turning-off maneuvers. Furthermore, exit ramps, particularly on freeways, have associated speed restrictions that frequently occur as a sequence of maximum speeds decreasing in stepwise fashion. However, when the respective exit ramp is not used by the driver, incorrect speed restrictions are communicated to the driver.
The above described limitations are more or less strongly pronounced, depending on the concept respectively realized in the particular case. Said limitations are to be considered in particular in this case when the aim is to dispense with the combination of a plurality of detection devices. On the other hand, the use of only a single environmental detection device is preferred from the point of view of cost, and also in order to increase the detection rates of the respective traffic sign recognition system.
Whereas the recognition of traffic signs by means of a camera or with the aid of navigation devices is generally known, there is to date no known effective and practical filtering and suppressing logic for solving the above described problems.